Latch checking means for circuit breaker mechanisms



June 17, 1941.

I. w. DYER ET AL 6, 98

LATCH CHECKING MEANS FOR CIRCUIT BREAKER MECHANISMS Filed Sept. 9, 1959 2 Sheets-Sheet 1 INVENTORS Z/ay/h/flyer dad ATTORNEY June 17, 1941. w DYER ET AL 2,246,298

LATCH CHECKING MEANS FOR CIRCUIT BREAKER MECHANISMS Filed Sept. 9, 1939 2 Sheets-Sheet 2 WITNESSES: INVENTOR S ATTORNEY Patented June 17, 1941 UNlTE. STATES PATENT OFFICE LATCH CHECKING MEANS FOR CIRCUIT BREAKER MECHANISMS Application September 9, 1939, Serial No. 294,048

19 Claims.

Our invention relates to mechanisms for tripping and closing a circuit breaker, and it has particular reference to trip-free mechanisms, in which the tripping latch, or other equivalent releasable holding-means, is arranged to disconnect a so-called trip-free lever which is utilized to reclose the breaker and to hold it closed in its normal position.

For a great many years, it has .been common, in many breakers having mechanisms of the abovedescribed trip-free class, to provide some sort of responsive means, responsive to the position of the mechanism, to either give a switchboard signal or provide a switch-interlock, presumably to show when the trip-free parts are in the relatched condition when the circuit breaker is open and ready to be reclosed. Such responsive means have all been deficient, however, some of them responding merely to a retrieved position of the trip-free lever, in which case it was assumed, without being positively known, that the trip-free lever was relatched ready for a reclosing stroke, and some of said responsive means being responsive merely to the position of the tripping latch, in which case, it could not be told whether the tripping latch had returned to its tripping position before, or after, the trip-free lever, or other part of the mechanism, had been retrieved to the proper position for a reclosing operation after a tripping operation.

It is the particular object of our present invention to overcome the aforesaid difliculties by providing a double-duty responsive means for mechanically responding to two conditions, and for responding only when both of said conditions are simultaneously fulfilled, said conditions being that the retrieved part is in its proper retrieved position, ready for a reclosure of the circuit breaker, and that the tripping latch is at the same time in its latching or holding position. Here, and elsewhere, the word latch is utilized in its generic sense of referring to any releasable mechanical holding-means.

In many substations, the operating engineers insist upon having a switchboard indication that an open circuit-breaker is certainly ready for a closing operation, at any moment when such an operation may be desired by the operator, without any guess-work or assumptions as to the proper coordination of the retrieving mechanism and the tripping latch; and in such cases, our improved double-duty responsive-means is utilized to provide such an indication.

In some substations, means are provided for instantaneously and automatically reclosing a circuit breaker as fast as possible, at least one time, after each tripping operation of the circuit breaker, such reclosure being initiated by an auxiliary switch-contact which is closed during the opening stroke of the circuit breaker; and in such cases, our improved double-duty responsive-means is utilized to control a suitable interlocking switch, in series relation to said auxiliary breaker-switch, to complete the energization of the reclosing coil, or other motive-means, as soon as the retrieved part is properly retrieved and tne latch is in its proper latching or holding position with respect to the retrieved part or the mechanism.

Heretofore, because of the above-described deficiencies of previous responsive means for providing such an interlock, it has been necessary, in fast reclosing installations, to provide an auxiliary switch, introducing a slight time-delay in order to make allowance for the incompleteness of the retrieving or latching indication, and to provide time for all of the parts to be in their proper positions, as otherwise the reclosing mechanism would make its closing stroke without carrying with it the moving contact of the circuit breaker, because the trip-free lever would not be properly latched in operative relation to the reclosing mechanism. In order to provide a reasonable factor of safety, it was necessary to make the time-delay, which was introduced by such auxiliary switches, longer than was actually necessary for the retrieved part and the latching part both to occupy their proper positions at the same time; and it is an object of our invention to avoid the necessity for any such time-delay switch, or for any uncertain race between two concurrently happening events, and to provide an instantaneously operating means for instantly energizing the closing coil, or other closing motive-means, as soon as, but not before, the retrieved part is in its retrieved position and the latching part is in its latching position.

With the foregoing and other objects in View, our invention consists in the parts, structures, combinations, systems and methods hereinafter described and claimed, and illustrated in the accompanying drawings, wherein Figure 1 is a somewhat diagrammatic elevational view illustrating a circuit breaker, with its operating mechanism, having an improved double-duty responsive means in accordance with our invention, for properly checking the position of the retrieved part as well as the position of the tripping latch,

Fig. 2 is a similar view of a portion of the I the bottom of the connecting link 3 between the Fig. 4 is a diagrammatic view of electric circuits and apparatus illustrating our invention in a system utilizing an automatic reclosing mechanism.

In Fig. 1, our invention is shown applied to 'an f oil circuit breaker I having aijr'open'ing and clos ing mechanism 2, the two parts being connected together by a vertical connecting link '3.--

The circuit breaker l comprises a tank: 4

containing oil 5 and having one or more pairs of insulated stationarycontacts 6, eachxpaircf stationary contacts 5 beingassociatedwith a moving contact '1 which is carried. .by.a liftrod 8, the top end of which is guided by. being. pivloted at 9 to an endofaafloating lever ii, the other end of which .is carried by. a. pivoted link 12 which is supported from. afixedv pivot.

l3. The floating lever. H is pivotally. connected, at an intermediate pointl, to .one end ofa main bell-crank H: which is intermediately sup.-

ported on a fixed pivot, H5. The other end of the main bell-crank I5 is pivotally connected toa toggle-lever link I! which, in turn, is;pivotally connected to a toggle-lever l8 whichis supported on a fixed pivot 19, andwhich isprovidedwith an extending arm 2|. which constitutes the closing lever of the breaker,. said-arm orlever 2i terminating in a pivoted connection 22 to .the top end of the connecting rodswhich leads to. the mechanism.2. a I; The mechanism 2 comprises abellecrank lever 23, one end of which is pivoted to the, bottom of the connecting link 3,.as indicated at 252. The bell-crank .lever23. is. supported, at. an inter: mediate point, on a fixed pivot 25. The other end of the bell-crank lever 23 is pivotally connected to a toggle-link 26 which,in, turn, is, pivotally connected to one end of a so-called trip-, free lever 21. The trip-free lever 2'! is ivoted, at an intermediate point, on a. so-called core: pin 28, which is carried by the top .ofv a corerod 29, thelower end of which is connected to the core or movable armature 3|,whichis acted upon by a closing coil 32 which is so arranged that the core 3| is lifted when the coil 32 is energized. l

The trip-free lever 21, at its end opposite the toggle-link 25, is provided with a latch-pin 33 which is engaged by a tripping-latch 34 which is pivotally supDOrted on a fixedpivot 35., In alignment with theposition of the latch-pin 33 in the closed position of the circuit breaker, as illustrated in Fig. 1, there is a fixed pin which cannot be seen in Fig. 1, but which is shown at 36 in Fig. 2. This fixed pin35 pivotallygupports an intermediate point in a main o-rclosing lever 37, one end of which is pivoted to the core-pin 28. r v

The tripping-latch 34 is connected to a. toggle link 38 which, in turn, is pivoted to a tripping lever 39, which is pivotally rnountedon a fixed pivot H, and which is providedwith a spring 42 which urges the tripping lever 38 in an anti-clockwise direction so as to move the toggle 38-39 just a little past its dead center,

' moving contact I of the circuit breaker into an so as to hold the tripping-latch 34 in its latching position. The tripping of the mechanism is effected by' causing the tripping lever 39 to be rotated in a clockwise direction, so as to break the toggle 3839, by any suitable means, such as a vertical trip-rod G3 which is shown, by way of illustration, as being lifted by any suitable tripping means, such as the core iii of a shunt tripping-coil 45.

The bell-crank lever 23, which is pivoted to mechanism and the breaker, is connected, at a point close to the connecting link 3, to the top end-4G of a powerful compression-spring M which servesas an accelerating-spring for moving the open position in which it is lowered down to the bottom of the tank 4.

The force of this accelerating-spring 4? is normally'absorbed, in the normal closed position of the breaker, not only by the tripping-latch 35 which holds the-end 33 of the trip-free lever 21, but also by a main latch of locking-lever 48, the top end of which is notched to underlie the corepin 28. The bottom end of the main latch or locking-lever 48 is mounted on a fixed pivot 39 and is provided with a spring 53 which tends to move the locking-lever clockwise into its latched position with respect to the core-pin 28.

V The locking-lever B8 is adapted to be disengaged from the core-pin 28 by means of the tripiree lever 2?, which swings in a counterclockwise direction about the core-pin 23 when its end 33 is released by the tripping-latch 3e. At a point immediately above the core-pin 23, the trip-free lever 21 is provided with a pin or protuberance 52 which engages the topend of the locking-lever 8 and moves the latter in a counterclockwise direction so that it becomes disengaged from the core-pin 28.

v In accordance with our invention, we provide a double-duty responsive-means for checking both the position of the tripping-latch 34 and the position of the trip-free lever 27. The position of the tripping-latch 36 is responded to by means of the tripping lever 33 which is at all times connected to thetripping-lever 34 through the toggle-link 38. The tripping lever 39 is provided with an integrally extending arm 54 which carries a switch-rod 55 terminating in the moving contact 58 or" an interlock-switch. The particular form of interlock-switch which is indicated in the drawings is of a type in which the moving contact 56 moves, plug-fashion, between two springniounted stationary contacts 51, the parts being so disposed that the interlock-switch 5651 is closed when the tripping lever 39 is rotated to the extreme limit of its counterclockwise movement, as shown in Fig. 1, at which time it is holding the-tripping-latch 34 in its latched position.

Inaccordance with our invention, it is necessary, also, to respond to the position of the tripfree lever 27, as will be subsequently explained more clearly when the operation of the mechanism is described. There are several forms which may be taken by the means for responding to the position of the trip-free lever 21. In the illust'ratedembodiment of our invention, our means for responding to the position of the trip-free lever 2'? takes the form of a locking-lever 53, one end of which is notched so as to engage a pin 59 on the tripping lever 39. Thelocking-lever 58 is pivotally mounted on the same fixed pivot 35 which supports the tripping-latch 34, and a locking-lever spring BI is provided for biasing the locking-lever 58 upwardly in readiness to engage the trip-lever pin 59 when the trip-lever 39 moves to its open or tripping position which it occupies when the tripping-latch 3% is moved to the right, away from the latch-pin 33 carried by the righthand end of the trip-free lever 21. By means of the locking-lever and the trip-lever pin 59, the tripipng-latoh 34 is held open, once it is opened, until the locking-lever 58 is released from engagement with the pin 59, thus preventing the immediate reciosure of the tripping-latch 34as soon as the trip-free lever 21 is released, and before the trip-free lever 27 is retrieved, as will be subsequently described in the explanation of the operation of the mechanism.

In accordance with our invention, the locking-lever 58 is released from its locking engagement (Fig. 2) with the trip-lever pin 59, by means of a lock-releasing lever 63, which is pivotally supported on the same fixed pin 41 which also supports the tripping lever 39. The lockreleasing lever 63 extends over to the left, so as to underlie the right-hand end of the trip-free lever 21 in the normal closed position of, the breaker, and also in the retrieved position of the trip-free lever as will be subsequently described, so that, when the trip-free lever 21 is retrieved, the last quarter-inch of its travel will depress the lock-releasing lever 63, so that a lug 64 on the latter will engage the top of the locking-lever 58 and depress the latter out of engagement with the trip-lever pin 59, so that the trip-lever 39 will then be permitted to return to its tripping position, at the same time closing the interlocking switch 5ii-5i', and thus affording an indication, both that the tripping-latch M is in its tripping position, and that the trip-free lever 21 is in its retrieved position.

In accordance with the usual practice, the movement of the moving contact! of the circuit breaker, and the movement of the closing-core 3| of the closing-mechanism are both utilized to actuate auxiliary contacts. This is diagrammatically illustrated in Fig. 1, in whichit is shown that the bell-crank lever 23 of the mechanism carries two auxiliary switches fiti and 66 which respond to the position of the moving contact 1 of the breaker, so that the auxiliary switch 65 is closed, and the auxiliary switch 66, is opened, at some time or times during the opening-stroke of the circuit breaker. In Fig. 1, we'also show our closing-lever 3'! as being provided with an extension 57 which actuates a mechanism-responsive auxiliary switch 88, which is closed when the mechanism is in its closed position, and which opens during the opening-stroke, or retrieving movement, of the mechanism. h

The operation of the illustrated circuit breaker and mechanism will now be described. Starting with the circuit breaker in its normal closed. position, as indicated in Fig. 1, tripping will be effected by lifting the trip-rod 43, as by energizing the shunt trip-coil 45 This will move the tripping-lever 39 in a clockwise direction, breaking the toggle 3839, and moving the tripping-latch 34 in a clockwise direction so that it will disenage the latch-pin 33 carried by the right-hand end of the trip-free lever 21. I

The tripping-latch 34 is provided with a slight- 1y inclined latching-surface (59 'in engagement with the latch-pin 33, so that the force of the powerful accelerating-spring 41 will tend strongly to kick the tripping latch 34 away from the tripping-pin 33 which is carried bythe righthand end of the trip-free lever 21. When the tripping-latch 34 kicks out, away from the trippin 33, the trip-lever 39 swings clockwise far enough for its pin 59 to be engaged by the notch II on the end of the locking lever 58, so that the tripping-latch 34 is momentarily held in its open position. In this open position of the tripping-latch 34, as shown in Fig. 2, the trippinglever 39 is in a clockwise-rotated position which result in the opening of the interlocking switch 56-51.

Under the influence of the accelerating-spring 47, as communicated through the bell-crank lever 23 and the toggle-link 25, the trip-free lever 21 will thereupon swing, in a counterclockwise direction, about the core-pin 23 as a pivot, the core-pin 28 being held stationary by means of the locking-lever 18. At some time during this trip-free swinging of the trip-free lever 21, its pin or shoulder 52 will engage the locking-lever t8 and push it out of locking engagement with the core-pin 28, so that the parts will now occupy the position shown in Fig. 2. In this position of the parts, the bell-crank lever 23 will have moved, in a clockwise direction, under the influence of the acceierating-spring il, thus elevating the connecting rod 3 which operates on the circuit-breaker linkage to depress the lift rod 8 which carries the moving contact 1 of the circuit breaker. completes the opening-operation of the circuit breaker.

As soon as the locking-lever it is moved out from under the core-pin 23, the latter immediately begins to drop, being pulled down by the weight of the moving core of the armature 31 of the closing-coil the closing coil 32 being deenergized. It should be understood that, while we have illustrated the parts, in Fig. 2, in the tripped-free position, the parts occupy this position for uch a small fraction of a second that the movement cannot be followed by the eye, as gravity immediately causes the core-pin 28 to drop.

During this dropping movement of the corepin 28, the bell-crank lever 23 remains stationary, after it completes the opening-movement of the circuit breaker, and the fixed pin 36 (Fig. 2) of the closing-lever 37 remains stationary, so that the core-pin 28 swings down in an are controlled by the length of the closinglever 31. The trip-free lever 2'! is carried by the downwardly moving core-pin 28 and this tripfree lever 21 swings at various angles controlled by its connection to the toggle-link Elwhich is carried by the bell-crank lever 23 during the downward swinging-movement of the core-pin 28, so that eventually, the trip-free lever 21 is swung or retrieved into a position when it is again parallel to the closing lever 31, as shown in Fig. 3, although the two parallel levers are now, in their open position, at an angle to their closed position which was shown in Fig. 1. When referring to the parallelism of the tripfree lever 2'! and the closing lever 37, we refer to the main portions of these levers, between the core pin 28 and the pins 33 and 36, respectively. In the retrieved position of the trip-free lever 21, the latch-pin 33 which is carried by this trip-free lever swings down into substantial alignment with the fixed pivot-pin 35 of the closing-lever 31.

The last quarter-inch, more or less, of the retrieving stroke of the trip-free lever 2?, as its right-hand end is moving downwardly, results in the depression of the lock-releasing lever 63 against the bias of its spring 13. This releases the locking-lever 53 from the trip-lever pin 59,

permitting the trip-lever 39 to move in a counter-.

clockwise direction, under the influence of its spring 22, thus returning the tripping-latch 34 to its latching position in which it holds the latch-pin 33 down, so that the trip-free lever 21 is retained in its retrieved position. The counterclockwise movement of the trip-lever 39 looks the toggle 3339 moving it just slightly beyond dead center, so that the tripping-latch 34 cannot be again disengaged until this toggle 38-39 is again broken. i

- In accordance with our invention, the trip-lever 38, in returning to its locked-toggle position, closes the interlock contacts 5657, thus affording-a positive indication "that the tripping-latch 34-is in its latched position and that the tripfree lever 27 is in its retrieved position.

- The closing of the circuit breaker is effected by a movement of the closing lever 31 about its fixed pivot 35 (Fig. 2). This closing lever can be moved-either by suitable manual means (not shown) 7 or by the energization of the closing-coil 32 which lifts the core 3| and'the core-pin28, thus restoring the circuit breaker toits closed position as illustrated in Fig. 1, the parts being finally held in the closed position by means of the locking lever 38 which engages under the corepin 28 and holds it up. a

Typical electrical connections for the circuit breakeni are shown in Fig. 4. In the application of our invention which is illustrated in Fig. 4, the circuit breaker I is three-pole, and its main contacts 6-7 are connected in a three-phase line '85 so as to connect and disconnect said line to and from a three-phase bus 16. An automatic, fault-responsive relay-mechanism is shown, as symbolized by a rectangle Ti and a relay-contact i8, represented as being controlled, in response to the line-current and the line-voltage, by means of a line-current transformer 89 and a bank of line-potential transformers N. The automatic protective-relay contact '58 is shunted by a pushbutton 82 which may be actuated for manual tripping. When either the relay-contact T8 or the push-button 82 is closed, the trip-coil 45 is energized from a suitable source, such as a local battery 33, with the auxiliary switch-contact 66 of the circuit breaker connected in series with the tripping coil 35. As shown, there is usually also provided, in the tripping circuit, a contactor switch 84 which seals itself in, through makecontacts 35, so as to protect the light-weight contacts l8 and 82 from burning, the tripping-circuit being finally interrupted by the auxiliary switch 66.

In the application of our invention shown in Fig. 4, we have shown two different means for initiating the energization of the closing-coil 32 of the mechanism. One closing-means is a manually controlled push-button 86 which is connected in series with our double-duty or dualresponsive latch-checking interlock EEG-57. The other closing-means is an instantaneously operative automatic closing-means which initiates the closing-operation in response to the closure of the auxiliary switch 65 which closes during the opening-stroke of the circuit-breaker. The aux iliary switch 65 is connected in series with either a manual or automatic disconnect-switch 87, the two switches 65 and 81 being shunted around the push-button 86, so that they are also in series with our dual-purpose latch-checking interlock 6-51.

As soon as a circuit is completed, either through the push-button 86 and the interlock 55-51, or through the auxiliary switch 65 and the interlock 56-51, this circuit is utilized to energize the actuating coil 38 of anoperating-relay 0, from the battery 83, in series with a back-contact 89 of a releasing-relay R. The energization of the operating-relay 0 closes a front-contact 9| which energizes the closing-coil 32 from the battery 83, and it also closes a front-contact 92 which bypasses the contacts 86, 565l, or 65,56-51 which initiated. the energization of the operating-re-- lay O. i

It will be understoodthat, before the dualpurpose latch-checking interlock Ei5l can be reclosed, the circuit breaker I must be opened. the movable parts must be in their retrieved position,.and the trip-free tripping-latch 34 must be in its latching position. In the diagrammatic representation in Fig. 4, we have not undertaken to show the complicated retrieving mechanism which is fully shown and described in connection with Figs. 1 to 3, but we desire the diagrammatic I illustration in Fig. 4 to illustrate such a mechanism.

When the dual-purpose latch-checking interlocking switch 53-51 is closed, therefore, the mechanism-responsive auxiliary switch 63 is necessarily in its open position, and it does not close until very nearly the end of the closing-stroke of the closing-core 3i which is drawn in by the closing-coil or solenoid 32. The closure'of the mechanism-responsive auxiliary switch 68 is utilized to energize the actuating coil 93 of the releasing-lever R, which thereupon opens its backcontact 89 and deenergizes the actuating coil -88 of the operating-relay 0. At the same time, the releasing-relay R closes a front-contact 94 which by-passes the mechanism-switch 68 so as to prevent pumping of the circuit breaker.

- Inresponse to the deenergization of the ac tuating coil 88 of the operating-relay 0, this relay promptly drops out, opening its front-contacts 9| and 92, which respectively deenergize the closing-coil 32 and deenergize the actuating coil 93 of the releasing-relay R, thus restoring the parts to their initial condition corresponding to the closed condition of the circuit breaker I as illustrated in Fig. 4.

The trip-free feature of the circuit-breaker mechanism 2 comes into play, during the closingstroke of the circuit breaker, in the event that the automatic fault-responsive protective relay lll8 is utilized, because, somewhere near the end of the closing-stroke of the circuit breaker, the moving contact 1 engages the stationary contacts 6, so that the power-line i5 is reconnected to the power-bus 16. If, now, there is still a fault on the line, the protective relay-contact 18 will again instantly pick up, re-energizing the trip-coil 45 so as to disengage the trippinglatch'34, thus instantly tripping out the breaker I, even though the closing-core 3| is still completing the last fraction of its closing-stroke.

In accordance with our invention, the doublyresponsive latch-checking and retrieved-checking interlock-switch 565l makes it possible to utilize an instantaneously operating relay 0 to energize the closingcoil 32 as soon as the latchchecking interlock 56-51 closes, without introducing any time-delay, and without running any risk of causing an ineffectual closing-stroke of the closing-core 3| when the latch 34 is not in eifectual engagement with the retrieved part Z'l .(Figs. 1-3). The auxiliary switch-contact 65 closes, in general, before the trip-free lever 21 (Figs. 1-3) is retrieved and relatched by the tripping-latch 34, so that the exact instant of initiating the closing-operation is usually under the control of the latch-checking interlock 56--51.

While we have illustrated our invention in a single preferred form of embodiment, and while we have illustrated a single preferred simplified form of electrical diagram therefor. we desire it to be understood that such illustration, and the accompanying description, are intended merely by way of illustration, and not by way of absolute limitation, as many changes. by way of substitution, addition and omission, can be made by those skilled in the art without departing from some of the essential features of our invention. We desire, therefore, that the appended claims shall be accorded the broadest construction consistent with their language and the prior art.

We claim as our invention:

1. Trip-free mechanism for controlling the operation of the moving contact of a circuit breaker; comprising a closing motive-means movable between an open position and a closed position; mechanical coupling-means between said closing motive-means and said moving con-' tact of the breaker; a tripping releasable mechanical holding-means for holding a predetermined portion of said mechanical coup-lingmeans in a predetermined relationship necessary to the transmitting of a pressure, in the closing direction, between the closing motive-means and the moving contact of the breaker; said mechanical coupling-means including a main releasable mechanical holding means for normally holding said moving contact of the breaker and said closing motive-means in their closed positions at a time when said tripping holding means is in its holding condition; tripping means for actuating said tripping releasable holding-means to its released condition; means operative as a consequence of the release of said tripping holding-means to release the main holding-means, to move the closing motive-means to its open position, and to restore said predetermined portion of the mechanical coupling-means to a predetermined relationship necessary to the transmitting of a pressure, in the closing direction, between the closing motive-means and the moving contact of the breaker; means for restoring said tripping releasable mechanical holding-means to its holding condition upon such restoration of said predetermined portion; and means for energ zing said closing motive-means for causing the same to move to its closed position; said tripfree mechanism being characterized'by having a double-duty interlock-means for mechanically responding to two conditions, and for responding only when both of said conditions are simultaneously fulfilled, said conditions being that the predetermined portion of the mechanical coupling-means is restored to said predetermined relationship and that the tripping releasable holding-means is restored to its holding condition with respect to said predetermined portion, and electric-circuit means for removing an impediment against the effective closing-energization of said closing motive-means when said interlockmeans is in a responsive condition.

2. Trip-free mechanism for controlling the operation of the moving contact of a circuit breaker, comprising a closing motive-means mov able between an open position and a closed posi tion, a main lever permanently mechanically coupled to said closing motive-means, a trip-free lever permanently mechanically coupled to said moving contact of the breaker, means for pivoting said levers for independent pivotal movements, a main latch for latching said main lever in a closed position, a tripping latch for latching said trip-free lever in a position substantially parallel to said main lever, tripping means for disengaging said tripping latch whereby said tripi'ree lever will move free of said main lever while the moving contact of-the breaker starts to move in the opening direction, vmeans responsive to the opening movement of the t ip-free lever for disengaging the main latch, retrieving means operative upon the disengagement of the main latch for moving the main le er and the mechanically coupled closing motive-means to the open position and for simultaneously restoring a relation of substantial parallelism to the two levers, but at an angle to the closed positions of both levers, means for biasing the tripping latch toward its latching position whereby said tripping latch is restored to its operative latching position in the substantially parallel open positions of the two levers, and means for energizing said closing motive-means for causing the same to move to its closed position, carrying with it the two levers and the moving contact of the breaker, said trip-free mechanism being characterized by having a double-duty interlock-means for mechanically responding to two conditions, and for responding only when both of said conditions are simultaneously fulfilled, said conditions being that the two levers are in a relation of substantial parallelism with respect to each other and that the tripping latch is in an operative latching position, and electric-circuit means for removing an impediment against the effective closing-energization of said closing motive-means when said interlock-means is in a. responsive condition,

T ip-free mechanism for controlling the cper on of the moving contact of a circuit breaker; c mprising a closing motive-means movable between an open position and a closed po tion; mechanical coupling-means between said closing motive-means and said moving contact of the breaker; a tripping releasable meiical holding-means for holding a predeter- 1, mod portion of said mechanical coupling- 1118211152 in a predeermined relationship necessary to the. transmitting of a pressure, in the closing direction, between the closing motive-means and the moving contact of the breaker; said mechanical coupling-means including a main releasable mechanical holding-means for normally holding said moving contact of the breaker and said closing motive-means in their closed positions at a time when said tripping holding-means is in its holding condition; tripping means for actuating said trippingv releasable holding-means to its released condition: means operative as a consequence of the release of said tripping holdingmeans to release the main holding-means, to move the closing motive-means to its open position, and to restore said predetermined portion of the mechanical coupling-means to a predetermined relationship necessary to the transmitting of a pressure, in the closing direction, between the closing motive-means and the moving contact of the breaker; means for mechanically preventing said tripping releasable mechanical holding-means from returning to its initial untripped holding-position until said closing mogive-means has substantially completed its opening movement and for thereupon restoring said tripping releasable mechanical holding-means to itsholding condition with respect to said predetermined portion; an interlock-means mechanically responsive to said restoration of the tripping releasable mechanical holding-means to its holding-position with respect to said prede-' termined portion; means for energizing said closing motive-means for causing the same to move to its closed position; and electric-circuit; means for removing an impediment against the effective closing-energization of said closing motive-means when said interlock-means is in a responsive condition.

4. Trip-free mechanism for controlling the o eration of the moving contact of a circuit breaker, comprising a closing motive-means movable between an open position and a closed position, a main lever permanently mechanically coupled to said closing motive-means, a trip-free lever permanently mechanically coupled to said moving contact of the breaker, means for pivoting said levers for independent pivotal movements, a main latch for latching said main lever in a closed position, a tripping latch for latching said tripfree lever' in a position substantially parallel to said main lever, tripping means for disengaging said trip-ping latch whereby said trip-free lever Will move free of said main lever while the moving contact of the breaker starts to move in the opening direction, means responsive to the opening movement of the trip-free lever for disengaging the main latch, retrieving means operative upon the disengagement of the main latch for moving the main lever and the mechanically coupled cIosing'motive-means to the open position and for simultaneously restoring a relation of substantial parallelism to the two levers, but at an angle tothe closed positions of both levers, means formechanically preventing said tripping latch from' returning to its initial untripped latching position until said closing motive-means has substantially completed its opening movement and for thereupon restoring said tripping latch to its latched position in engagement with the trip-free lever, an interlock-means mechanically responsive to said restoration of the tripping latch to its latched position in engagement with the trip-free lever, means for energizing said closing motive-means for causing the, same to move'to its closed position, and electric-circuit means for removing an impediment against-the efie'ctive closing-energization of said closing motive-means when said interlock-means is in a responsive condition.

5. The invention as defined in claim 1, characterized by the means for energizing the closing motive-means to close the same comprising an auxiliary switch-contact which is normally automatically closed during the opening movement of the moving contact of the breaker.

6. The invention as defined in claim 2, characterized by the means for energizing the closing motive-means to close the same comprising an auxiliary switch-contact which is normally automatically closed during the opening movement of the moving contact of the breaker.

'7.-The invention as defined in claim 3, characterized by the means for energizing the closing motive-means to close the same comprising an auxiliary switch-contact which is normally automatically closed during the opening movement of the moving contact of the. breaker.

, 8. The inventionnas defined in claim 4, characterized by the means for energizing the closing motive-means to close the same comprising an auxiliary switch-contact which is normally automatically closed during the opening movement of the moving contact of the breaker.

9. Trip-free 'mechanism for controlling the operation of the moving contact of a circuit breaker; comprising a closing motive-means movable between an open position and a closed position; mechanical coupling-means between said closing motive-means and said moving contact of the breaker; 'a tripping releasable mechanical holding-means for holding a predetermined portion of said mechanical couplingmeans in a predetermined relationship necessary to'the transmitting of a pressure, in the closing direction, between the closing motive-means and the moving contact of the breaker; said mechanical coupling means including'a main releasable mechanical holding-means for normally holding said movingcontact of the breaker and said closing motive-means intheir closed positions at a time when said tripping holding-means is in 1 its holding condition; tripping means for actuating said tripping releasable holding-means to its released condition; means operative as a consequence of the release of said tripping holdingmeans to release the main holding-means, to move the closing motive-means to its open position, and to restore said predetermined portion of the mechanical coupling-means to a predetermined relationship necessary to the transmitting of a pressure, in the closing direction, between the closing motive-means and the moving contact of the breaker; and means for restoring said tripping releasable mechanical holding-means to its holding condition upon such restoration of said predetermined portion; said trip-free mechanism being characterizedby having a doubleduty latch-checking switch-contact device for mechanically responding to two conditions, and for responding only when both of said conditions are simultaneously fulfilled, said conditions being that the predetermined portion of the mechanical coupling-means is restored to said predeter mined relationship and that the tripping releasable holding-means is restored to its holding condition with respect to said predetermined portion.

l0. Trip-free mechanism for controlling the operation of the moving contact of a circuit breaker, comprising a closing motive-means movable between an open position and a closed position, a main lever permanently mechanically coupled to said closing motive-means, a trip-free lever permanently mechanically coupled to said moving contact of the breaker, means for pivoting said levers for independent pivotal movements, a main latch for latching said main lever in a closed position, a tripping latch for latching said trip-free lever in a position substantially parallel to said main lever, tripping means for disengaging said tripping latch whereby said trip-free lever will move free of said main lever while the moving contact of the breaker starts to move in the. openingdirection, means respon-' 1 sive. to the'opening movement of the trip-free lever for disengaging the main latch, retrieving means operative upon the disengagement of the main latch for moving the main lever and the mechanically coupled closing motive-means to the open position and for simultaneously restoring a relation of substantial parallelism to the two levers, but at an angle to the closed positions of both levers, and means for biasing the tripping latch toward its latching position whereby said tripping latch is, restored to its operative latching position in the substantially parallel open positions of the two levers, said trip-free mechanism being characterized by having a double-duty latch-checking switch-contact device for mechanically responding to two conditions, and for responding only when both of said conditions are simultaneously fulfilled, said conditions being that the two levers are in a relation of substantial parallelism with respect to each other and that the tripping latch is in an operative latching position.

11. Trip-free mechanism for controlling the operation of the moving contact of a circuit breaker, comprising a closing motive-means movable between an open position and a closed position; mechanical coupling-means between said closing motive-means and said moving contact of the breaker; a tripping releasable mechanical holding-means for holding a predetermined portion of said mechanical coupling-means in a predetermined relationship necessary to the transmitting of a pressure, in the closing direction, between the closing motive-means and the moving contact of the breaker; said mechanical coupling-means including a main releasable mechanical holding-means for normally holding said moving contact of the breaker and said closing motive-means in their closed position at a time when said tripping holding-means is in its holding condition; tripping means for actuating said tripping releasable holding means to its released condition; means operative as a consequence of the release of said tripping hold ing means to release the main holding-means, to move the closing motive-means to its open position, and to restore said predetermined portion of the mechanical coupling means to a predetermined relationship necessary to the transmitting of a pressure, in the closing direction, between the closing motive-means and the moving contact of the breaker; means for mechanically preventing said tripping releasable mechanical holding-means from returning to its initial untripped holding-position until said clos ing-motive-means has substantially completed;

its opening movement and for thereupon restoring said tripping releasable mechanical holdingmeans to its holding condition with respect to said predetermined portion; and a latch-checking switch-contact device mechanically responsive to said restoration of the tripping releasable mechanical holding means to its holding-position with respect to said predetermined portion.

12, Trip-free mechanism for controlling the operation of the moving contact of a circuit breaker, comprising a closing motive-means movable between an open position and a closed position, a main lever permanently mechanically coupled to said closing motive-means, a trip-free lever permanently mechanically coupled to said moving contact of the breaker, means for pivoting said levers for independent pivotal movements, a main latch for latching said main lever in a closed position, a tripping latch for latching said trip-free lever in a position substantially parallel to said main lever, tripping means for disengaging said tripping latch whereby said tripfree lever will move free of said main lever while the moving contact of the breaker starts to move in the opening direction, means responsive to the opening movement of the trip-free lever for disengaging in, in latch, retrieving means operative upon the disengagement of the main latch for moving the main lever and the mechanically coupled closing motive-means to the open position and for simultaneously restoring a relation of substantial parallelism to the two levers, but at an angle to the closed positions of both levers, means for mechanically preventing said tripping latch from returning to its initial untripped latching position until said closing motive-means has substantially completed its opening movement and for thereupon restoring said tripping latch to its latched position in engagement with the trip-free lever, and a latch-checking switchcontact device mechanically responsive to said restoration of the tripping latch to its latch position in engagement with the trip-free lever.

13. In combination, a circuit-breaker provided with a movable contact; actuating mechanism therefor comprising a biased actuating member the release of which, from a predetermined position, is necessary in order to effect the opening of the circuit-breaker; restraining means for releasably restraining said actuating member in its aforesaid predetermined position; trippingmeans for actuating said restraining-means to its released position; means for retrieving said actuating member to its aforesaid predetermined position; means for restoring said restrainingmeans to its restraining position; and a doubleduty latch-checking switch-contact device for mechanically responding to two conditions, and for responding only when both of said conditions are simultaneously fulfilled, said conditions being that the actuating member is retrieved' substantially to its aforesaid predetermined position and that the restraining-means is restored substantially to its restraining position.

14. In combination, a circuit-breaker provided with a movable contact; actuating mechanism therefor comprising a biased actuating member the release of which, from a predetermined position, is necessary in order to effect the opening'of the circuit-breaker; restraining-means for releasably restraining said actuating member in its aforesaid predetermined position; an auxiliary holding-means having a holding position for holding said restraining-means in its restraining position; tripping-means for moving said auxiliary holding-means to a tripped position in which it releases said restraining-means: means for retrieving said actuating member to its aforesaid predetermined position; means for causing said restraining-means to return to its restraining position; means for restoring said auxiliary holding-means to its aforesaid holding position; and a double-duty latch-checking switch-contact device for mechanically responding to two conditions, and for responding only when both of said conditions are simultaneously fulfilled, said conditions being that the actuating member is retrieved substantially to its aforesaid predetermined position and that both said restraining-means and said auxiliary ho1ding-means are restored substantially to their restraining and holding positions.

15. In combination, a circuit-breaker provided with a movable contact; actuating mechanism therefor comprising a biased actuating member the release of which, from a predetermined position, is necessary in order to eiTect the opening of the circuit-breaker; restraining-means for releasably restraining said actuating member in its aforesaid predete mined position; trippingmeans for actuating said restraining-means to its released position; means for retrieving said actuating member to its aforesaid predetermined position; means for preventing said restrainingmeans from returning to its restraining position until said actuating member has returned substantially to its aforesaid predetermined position and'for thereupon restoring said restraining-means to its restraining position; and a latch-checking switch-contact device responsive to the movement of said restraining-means to or from its restraining position.

16. In combination, a circuit-breaker provided with a movable contact; actuating mechanism therefor comprising a biased actuating member the release of which, from a predetermined-position, is necessary in order to effect the opening of the circuit-breaker; restraining-means for releasably restraining said actuating member in its aforesaid predetermined position; means for biasing said restraining-means toward its restraining position; tripping-means for actuating said restraining-means to its released position; means for retrieving said actuating member to its aforesaid predetermined position; means for preventing said restraining-means from returning to its restraining position until said actuating member has returned substantially to its aforesaid predetermined position; and a latch-checking switch-contact device responsive to the movement of said restraining-means to or from its restraining position.

1.7. In combination, a circuit-breaker provided with a movable contact; actuating mechanism therefor comprising a biased actuating member the release of which, from a predetermined position, is necessary in order to effect the opening of the circuit-breaker; restraining-means for releasably restraining said actuating member in its aforesaid predetermined position; an auxiliary holding-means having a holding position for holding said restraining-means in its restraining position; tripping-means for moving said auxiliary holding-means to a tripped position in which it releases said restraining-means; means for retrieving said actuating member to its aforesaid predetermined position; means for restoring said restraining-means and said auxiliary holdingmeans to their restraining and holding positions, respectively; means for preventing said auxiliary holding-means from returning to its aforesaid holding position untilsaid actuating member has returned substantially to its aforesaid predetermined position; and a latch-checking switchcontact device responsive to the movement of said auxiliary holding-means to or from its aforesaid holding position.

18. In combination, a circuit-breaker provided with a movable contact; actuating mechanism therefor comprising a biased actuating member the release of which from a predetermined position, is necessary in order to effect the opening of the circuit-breaker; restraining-means for releasably restraining said actuating member in its aforesaidpredetermined position; an auxiliary holding-means having a holding position for holding said restraining-means in its restraining position; means for biasing said restrainingmeans and said auxiliary holding-means toward their restraining and holding positions, respectively; tripping-means for moving said auxiliary holding-means to a tripped position in which it releases said restraining-means; means for retrieving said actuating member to its aforesaid predetermined position; means for preventing said auxiliary holding-means from returning to its aforesaid holding position until said actuating member has returned substantially to its aforesaid predetermined position; and a latch-checking switch-contact device responsive to the movement of saidauxiliary holding-means to or from its aforesaid holding position.

l;9.-In combination, a circuit-breaker provided with a movable contact; actuating mechanism therefor comprising a biased actuating member the release of which, from a predetermined position, is necessary in order to effect the opening of the circuit-breaker; restraining-means for restraining said actuating member in its aforesaid predetermined position in such manner that the bias of said actuating member tends to push said restraining-means out of its restraining position; an auxiliary holding-means having a holding position for holding said restraining-means in its restraining position; means for biasing said auxiliary holding-means toward its aforesaid holding position; means for moving said auxiliary holding-means to a tripped position in which it releases said restraining means; means for retrieving said actuating member to its aforesaid predetermined position; means for causing said restraining-means to return to its restraining position; means for preventing said auxiliary holding-means from returning to its aforesaid holding position until said actuating member has returned substantially to its aforesaid predetermined position; and a latch-checking switchcontact device responsive to the movement of said auxiliary holding-means to or from its aforesaid holding position. 7

. LLOYD W. DYER.

THOMAS A. JORDAN. 

